<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<form action="javascript:" method="post">
			<select name="" id="s1" size="4" multiple>
				<option value="">篮球</option>
				<option value="">足球</option>
				<option value="">排球</option>
				<option value="">网球</option>
			</select>
			
			<input type="button" id="btn" value=">>" />
			
			<select name="" id="s2" size="4" multiple>
				
			</select>
		</form>
		
		<script type="text/javascript">
			btn=document.getElementById('btn')
			s1=document.getElementById('s1')
			s2=document.getElementById('s2')
			
			opts=s1.options;
			btn.onclick=function(){
				idx=s1.selectedIndex;
				s2.add(opts[idx]);
			}	
		</script>
	</body>
</html>
